Documentary filmmaker Errol Morris, whose “Tabloid” opened Friday, is usually on the “Q” side of Q&A’s. So he’s endearingly considerate to the journalists who must interview him.

During our 30-minute talk, he apologizes four times, tells me twice how he strives not to repeat stories from older interviews, and generously defends reporters who begin with the banal “What got you interested in this story?” He even admits to a nervous interview-opening tic of his own.

When he was working on his 2008 Abu Ghraib documentary, “Standard Operating Procedure,” he recalls that journalist Philip Gourevitch sat in on a lot of the interviews. “At one point he asked me, ‘Do you know you always start the same way?’ Evidently, according to Philip, I always say ‘I don’t know where to start . . .’ ”

Morris has told this story before, actually. But it hints at what makes his interviews so successful: Like Columbo, Morris (a frumpy man who used to be a private investigator himself) masks his acuity with apparent ignorance or aimlessness, leading subjects to admit things they’ve never revealed to more goal-oriented interrogators.

The sensationalistic “Tabloid” lacks the kind of “gotchas” that highlighted Morris’s hit cop-killer investigation, “The Thin Blue Line.” That’s fine with him. He’s less concerned with the core mystery of “Tabloid” — whether former beauty queen Joyce McKinney kidnapped her ex-boyfriend — than with the bizarre ways McKinney mythologizes her own life: In the course of the film, she produces an astonishing repertoire of excuses and evasions, a funhouse-mirror exaggeration of ordinary self-deception.

US director Errol Morris poses with his Silver Bear, the Jury Grand Prix, during the awarding ceremony at the 58th Berlinale International Film Festival in Berlin, in 2008. Morris was awarded for his movie 'Standard Operation Procedure'. (TOBIAS SCHWARZ/ASSOCIATED PRESS)

The probing footage of McKinney — enough for years of psychotherapy — all came from a single meeting. Asked how that can be, Morris says, “It’s surprised me over the years, how much can come out in one interview.”

Well-honed strategies help. Morris is famous for shutting up and letting others talk, trusting them to fill awkward silences with unexpected revelations. He invented the Teleprompter-like Interrotron, which lets people see his face while looking directly into the camera. And, unlike the reporters who get 30 minutes apiece to interview him, Morris talks to people for a very long time — up to 11 hours in one sitting.

“I used to joke that when we both started hallucinating, maybe things started to happen,” he laughs. But he now suspects that “having these unending interviews is really not such a good thing.”

He earns his subject’s time by being well prepared. After interviewing Robert S. McNamara for his Oscar-winning “The Fog of War,” Morris recalls, the former defense secretary “told me he was surprised I had actually read his books. He said that was usually not the case. When that interview started, he had only agreed to give me a half-hour. Then that was extended to an hour, and in turn extended to two-hours-plus. Then he agreed to come back for a second day.”

Morris has concluded that “there’s no way to conduct an interview correctly. It’s a human relationship. If there was a way to have human relationships correctly, maybe we could interview correctly.”

However sympathetic he is to interviewers, even Morris can pretend not to understand a challenging question. He’s a prolific director of TV commercials, some for companies that have become synonymous with scandal. I ask if there are any he regrets — a campaign for the insurance giant AIG, for instance, in which the company (whose bad decisions would require the largest bailout in U.S. history) claims that “the greatest risk is not taking one.”

Instead of offering remorse for burnishing the image of a corporation that helped trigger a global financial crisis, Morris focuses on a single creative disagreement he and AIG had: He didn’t like an on-screen graphic in which the word “risk” was scratched out. “I would’ve liked them to correct that one small detail,” he laments, “because I thought it makes the ads less powerful. I think those are beautiful ads, really beautifully shot.”

“I have declined to do ads. There’s a whole list of ads that I did not take,” he says when pressed, although he won’t name any client he has turned down.

“I’m doing a feature with [“This American Life” host] Ira Glass,” he reveals, a surprise given the failure of his only previous fiction film, 1991’s “The Dark Wind.” The new film is based on the life of cryonics pioneer Bob Nelson and will star Paul Rudd.

“You could call it a tabloid story,” he says, noting the Weekly World News-ish title of Nelson’s memoir, “We Froze the First Man.”

But Morris doesn’t need Glass to find macabre stories for him. He has lived a few, or come close: He and German film director Werner Herzog, while researching serial killers, once plotted to dig up the coffin of murderer Ed Gein’s mother. (Gein had stolen corpses; Morris wondered if he had sneakily taken his mother’s as well.) Years later, Morris publicly apologized for not meeting Herzog, who had been willing to go through with the dig, at the appointed hour. Was Morris sincere about that apology?

“I was, actually,” he says today.

Does he wish he had gone through with it?

“Um, no. I don’t think that if I’d shown up we would have done it,” he admits. “It was a time in my life when I could ill afford to be arrested for grave-robbing.”

“By the way,” he adds hastily, “I think I’m at that same place in my life right now.” However congenial he is in interviews, it seems, the filmmaker has no interest in becoming the subject of somebody else’s Errol Morris-style true-crime documentary.